"How do you control them in the first place?"
He sighed. "It isn't really what you would call controls," he said. "It's just the best I can do to keep them from spreading."
"But—you said sometimes you separate metals, sometimes you get energy. How do the demons know which you want them to do, if you say you can't control them?"
"How do you make an apple tree understand whether you want it to grow Baldwins or Macintoshes?"
gawked at him. "Why—but you don't, Greek! I mean it's either one or the other!"
"Just so with demons! You're not so stupid after all, are you? It's like improving the breed of dogs. You take a common ancestral mutt, and generations later you can develop an Airedale, a dachshund or a Spitz. How? By selection. My demon entities grow, they split, the new entities adapt themselves to new conditions. There's a process of evolution. I help it along, that's all."
He took the little slab of gold from me, brooding.
Abruptly he hurled it at the wall. "Gold!" he cried wildly. "But who wants it? I need help, Virgie! If gold will buy it from you, I'll pay! But I'm desperate. You'd be desperate too, with nothing ahead but a sordid, demeaning death from young age and a—"